• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 636
  • 627
  • 109
  • 60
  • 57
  • 31
  • 13
  • 11
  • 11
  • 11
  • 11
  • 11
  • 11
  • 11
  • 9
  • Tagged with
  • 1765
  • 661
  • 281
  • 263
  • 249
  • 222
  • 141
  • 140
  • 122
  • 122
  • 100
  • 99
  • 94
  • 91
  • 91
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
121

Phylogeny of Pempheridae inferred from sound-producing structure and DNA sequences

Jiang, Yu-xuan 19 August 2010 (has links)
According to previous morphological studies on percoid phylogenies, Pempheridae may have a closer relationship to Glaucosomatidae, Teraponidae, Bramidae, Carangidae, Centropomidae, Kyphosidae, Leiognathidae, Menidae, Nandidae, Percichthyidae, Polynemidae, Sciaenidae or Toxotidae. About 10% of 515 fish families are soniferous and Pempheridae is one of the soniferous families in Percoidei. A pair of slits has been found at the anterodorsal sides of the swimbladder in Glaucosomatidae, Teraponidae and Pempheridae, and it suggests that they have closer relationship. And preliminary study on molecular phylogeny has evidence supporting that Glaucosomatidae and Pempheridae are sister goups. In this study, I compared the sonic muscle, swimbladder morphology, slit and associated structures in percoid soniferous fishes, including Pempheridae, Glaucosomatidae, Teraponidae, Sciaenidae, Priacanthidae, Haemulidae, Cichlidae and Pomacentridae. I found that there are synapomorphic characters in Pempheridae, Glaucosomatidae and Teraponidae; the slits and elastic tissue in the swimbladder are similar, and are limited to these three families. Furthermore, 16S rRNA, COI, Cytb and Rhodopsin gene sequences data were used for phylogenetic studies. And the results reveal that Pempheridae and Glaucosomatidae are sister groups and they are not closely related to Teraponidae. Therefore, the similary of sonic system in Teraponidae, Pempheridae and Glaucosomatidae may have evolved at least twice in the Percoidei and convergent evolution might also have taken placed.
122

Morphology of the Mucous Pouches and Taxonomic Study of Cistopus sp. (Cephalopoda: Octopodidae) from Taiwan

Liao, Jian-Xiang 22 June 2003 (has links)
Cistopus sp. is a medium to large octopod and it is common in the fish markets of Taiwan. The diagnostic character of the genus Cistopus is the possession of eight mucous pouches in the web between the base of each arm. However, researches on this special structure were absent. This study is to describe the morphological characters of Cistopus sp. from Taiwanese waters and to examine the mucous pouch histologically. The mitochondrial COI gene sequences are used as a tool to analyze the phylogenetic relationships between Cistopus and other genera of the family Octopodidae. Based on the results of this study, the Cistopus of Taiwanese waters is different from the genuine C. indicus and the Cistopus of the Andaman Sea. Cistopus sp. is widely distributed from coastal Asia to India at least and presents sexual dimorphism in the openings of the mucous pouches. The inner wall of the mucous pouches is composed of columnar epithelial cells, and the mucus is secreted from the epithelial cells. The substance secreted from the inner wall is acid mucopolysaccharides. According to the phylogenetic analysis of the octopods COI DNA sequences, Cistopus is grouped with other members of subfamily Octopodinae to form a monophyletic group.
123

The study of fossil faunas in the Walanae Basin, Indonesia

Suyono. January 2009 (has links)
Thesis (M.Sc.-Res.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 106-115.
124

Using a complex model of sequence evolution to evaluate and improve phylogenetic methods

Holder, Mark Travis. January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.
125

Postcranial anatomy of Tanius sinensis Wiman, 1929 (Dinosauria; Hadrosauroidea) / Postkraniala anatomin hos Tanius sinensis Wiman, 1929 (Dinosauria; Hadrosauroidea)

Borinder, Niclas January 2015 (has links)
Tanius sinensis Wiman, 1929 was one of the first hadrosauroid or “duck-billed” taxa erected from China, indeed one of the very first non-avian dinosaur taxa to be erected based on material from the country. Since the original description by Wiman in 1929, the anatomy of T. sinensis has received relatively little attention in the literature since then. This is unfortunate given the importance of T. sinensis as a possible non-hadrosaurid hadrosauroid i.e. a member of Hadrosauroidea outside the family of Hadrosauridae, living in the Late Cretaceous, at a time when most non-hadrosaurid hadrosauroids had become replaced by the members of Hadrosauridae. To gain a better understanding of the anatomy of T. sinensis and its phylogenetic relationships, the postcranial anatomy of it is redescribed. T. sinensis is found to have a mosaic of basal traits like strongly opisthocoelous cervical vertebrae, the proximal end of scapula being dorsoventrally wider than the distal end, the positioning of the ventral apex of the supra-acetabular process of the ilium, posterodorsally to the ischial peduncle, the ratio between the proximodistal length of the metatarsal III and the mediolateral width of this element being greater than 4.5. Derived traits present in T. sinensis include curved dorsal surface of the scapula, arcuate fourth trochanter of the femur, cnemial crest of the tibia extending ventrally into the proximal half of the shaft, and the distal end of the fibula expanding into a club shape in lateral view. A potential autapomorphy is noted, being the caudal fusion of the medial and lateral condyles of the femur forming a completely enclosed “tunnel”. The body mass of the holotype of T. sinensis, is also estimated, and found to have been around 2950 kg. The phylogenetic analysis agrees with previous studies placing T. sinensis as a non-hadrosaurid hadrosauroid. Furthermore, in the phylogenetic analysis, T. sinensis is recovered as non-hadrosaurid hadrosauroid, forming a clade with Bactrosaurus johnsoni Gilmore, 1933, which shares the following unambiguous synapomorphies; the width of the orbital margin of the jugal being almost equally wide to that of the infratemporal margin of the bone; the ratio between the mediolateral width of the skull roof across the postorbitals and that across the quadrate cotyli of the paired squamosals being more than 1.20. / Den här uppsatsen handlar om Tanius sinensis Wiman, 1929 som levde under Kritaperioden i  Shan-dongprovinsen i nordöstra Kina. Tanius sinensis hörde till gruppen ”Anknäbbsdinosaurier” som ut- vecklades under början av Kritaperioden för mellan 130-100 miljoner år sedan. I slutet av Kritaperi- oden för ungefär 84 miljoner år sedan så blev de ”primitiva” ”anknäbbsdinosaurierna” bortträngda av de mer ”avancerade” ”anknäbbsdinosaurierna”. Tanius sinensis är viktig på så vis att den kan ha varit en ”primitiv” ”anknäbbsdinosaurie” som överlevde vid en tidpunkt när de flesta andra ”primitiva” ”anknäbbsdinsoaurier” hade trängts undan. För att få en bättre bild av T. sinensis anatomiska känne- tecken och en bättre bild av dess släktskapsförhållanden, så ombeskrivs anatomin hos den del av skelettet som inte omfattar kraniet. En släktskapsanalys görs också baserat på de kännetecken som jag själv och tidigare forskare  har  observerat  i  skelettet.  De  anatomiska  observationerna avslöjar en mosaik av ”primitiva” och mer ”avancerade” karaktärer, som tillsammans  med släktskapsanalysenpekar  på att T. sinensis var en sent överlevande ”primitiv”  ”anknäbbsdinosaurie”.
126

Algorithms and heuristics for combinatorial optimization in phylogeny

Ganapathysaravanabavan, Ganeshkumar 28 August 2008 (has links)
Not available / text
127

Patterns and processes of speciation in North American chorus frogs (Pseudacris)

Lemmon, Emily Claire Moriarty 28 August 2008 (has links)
During speciation, populations become spatially separated from each other by biotic or abiotic factors, and this leads to genetic divergence and reproductive isolation. Here, I study the process of speciation and the patterns resulting from this process in the chorus frogs (Pseudacris). I first lay the foundation for this work by constructing phylogenies based on molecular data. I then address broad-scale questions regarding the abiotic factors thought to drive speciation. I examine evolution of reproductive signals within a phylogenetic context, and finally, I address fine-scale questions regarding the completion of reproductive isolation in contact zones between recently-evolved species. In chapter 1, I estimate the phylogenetic relationships across the genus Pseudacris. I find that several species of unclear status (regilla, cadaverina, crucifer, ocularis) belong to this genus, and that P. ocularis is the sister species of P. crucifer. In chapter 2, I examine the phylogeography of a clade within Pseudacris, the trilling chorus frogs. I find support for at least nine species and delineate their geographic distributions. In chapter 3, I test geological and climatic hypotheses proposed to drive speciation in North American flora and fauna. By estimating divergence times in the trilling chorus frogs and correlating these divergences with timing of geologic events, I find that marine inundation of the Mississippi Embayment may have caused speciation in this group. Additionally, I find that climatic events led to reduced genetic variation rather than divergence within species. In chapter 4, I study the evolution of acoustic signals of all species of Pseudacris. Using a comparative method approach, I find that physiologybased call variables are more evolutionarily labile than morphology-based call variables. In addition, I find that sympatric signals are more different than allopatric signals, suggesting that these frogs have partitioned the acoustic niche. In chapter 5, I examine evolution of reproductive isolation between two chorus frog species in sympatry. I find that male signals show a repeated pattern of divergence in sympatry, and that different axes of the signal diverge in different populations, suggesting that heterospecific overlap may lead to reproductive isolation among conspecific populations. I also find that female preferences have evolved in sympatry, suggesting that divergence in the contact zone is due to reinforcement.
128

The isolation and characterization of triterpene saponins from Silphium and the chemosystematic and biological significance of saponins in the Asteraceae

Calabria, Lalita Maria, 1980- 29 August 2008 (has links)
Not available / text
129

Anatomy, ontogeny, and phylogeny of coelophysoid theropods

Tykoski, Ronald S. 29 August 2008 (has links)
Not available / text
130

Systematics, phylogeny and reproductive biology of Mitrephora (Annonaceae)

Weerasooriya, Aruna Dharmapriya. January 2001 (has links)
published_or_final_version / abstract / toc / Ecology and Biodiversity / Doctoral / Doctor of Philosophy

Page generated in 0.0303 seconds